Re: [PATCH v12 2/2] mm: page_alloc: reduce unnecessary binary search in memblock_next_valid_pfn

Hanjun Guo
2019-07-24T08:33:40Z

On 2019/7/23 16:33, Mike Rapoport wrote:
> On Tue, Jul 23, 2019 at 01:51:13PM +0800, Hanjun Guo wrote:
>> From: Jia He <hejianet@gmail.com>
>>
>> After skipping some invalid pfns in memmap_init_zone(), there is still
>> some room for improvement.
>>
>> E.g. if pfn and pfn+1 are in the same memblock region, we can simply pfn++
>> instead of doing the binary search in memblock_next_valid_pfn.
>>
>> Furthermore, if the pfn is in a gap of two memory region, skip to next
>> region directly to speedup the binary search.
> How much speed up do you see with this improvements relatively to simple
> binary search in memblock_next_valid_pfn()?

The major speedup on my platform is the previous patch in this patch set,
not this one, I think it's related to sparse memory mode for different
platforms.

Thanks
Hanjun